Instead of unrolling the code 16 times, unroll it 4 times and loop
over it 4 times. This gives the same 16 iterations, but at an expense
of less flash space.
* No weak link for modules. It only impacts _os and _time and is
already disabled for non-full builds.
* Turn off PA00 and PA01 because they are the crystal on the Metro
M0 Express.
* Change ejected default to false to move it to BSS. It is set on
USB connection anyway.
* Set sinc_filter to const. Doesn't help flash but keeps it out of
RAM.
Lightly tested:
* no matches (catch-all)
* standard address single address matches (even and odd positions)
* standard address mask matches
* only tested that extended doesn't match non-extended
Tested & working:
* Send standard packets
* Receive standard packets (1 FIFO, no filter)
Interoperation between SAM E54 Xplained running this tree and
MicroPython running on STM32F405 Feather with an external
transceiver was also tested.
Many other aspects of a full implementation are not yet present,
such as error detection and recovery.
I recently misdiagnosed a "maybe-uninitialized" diagnostic as a bug in
asf4. However, the problem was in our SPI code.
A special case for samr21 MCUs was being applied to same54p20a and possibly
other D5x/E5x MCUs, since the check was simply for pin PC19 existing at all.
Change the check to use the macro PIN_PC19F_SERCOM4_PAD0 which is only
defined if special function F of pin PC19 is SERCOM4 PAD0.
Reorganize the code a little bit so that brace-matching in editors is
not confused by the conditionalized code, including an unrelated change
for APA102_SCK's condition.
Revert the change to the Makefile that incorrectly attempted to silence
the diagnostic.
This is a slight trade-off with code size, in places where a "_varg"
mp_raise variant is now used. The net savings on trinket_m0 is
just 32 bytes.
It also means that the translation will include the original English
text, and cannot be translated. These are usually names of Python
types such as int, set, or dict or special values such as "inf" or
"Nan".
